[vulkan, android] Add feature of post-processing shaders on Android (#4348)

Very self-explanatory; implementation of the feature for post-processing shaders for Android (at least for now); will allow users to enhance the graphic quality of video games based on the use of multiple shaders adjustable, presets and more, inspired on the PPSSPP implementation, this feature adds 22 customizable shaders (1 pass) that lives on the overlay of the screen, which means that aside of the capability to chain multiple shaders on the screen, this doesn't have depths (pixel/ depth z-buffer) so it ensures the performance with it's use. Few shaders were a faithful port from PPSSPP with their respective attribution on the shader headers for their respective owners; and there are adaptations from public references/ cinematographic (Anime4K) and the rest are my own addition.

_Special Credits:_

1.- PPSSPP Team for their contribution on the public references for shaders: Henrik Rydgard, ShadX, SimoneT, KillaMaaki and guest(r).
2.- Niklas Haas.
3.- bloc97.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4348
Reviewed-by: lizzie <lizzie@eden-emu.dev>
Reviewed-by: Maufeat <sahyno1996@gmail.com>

1 files changed, 307 insertions, 0 deletions

diff --git a/src/video_core/post_processing/fx_effect.cpp b/src/video_core/post_processing/fx_effect.cpp
new file mode 100644
index 0000000000..7bb36b0467
--- /dev/null
+++ b/src/video_core/post_processing/fx_effect.cpp
@@ -0,0 +1,307 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <algorithm>
+
+#include "bundled_fx_effects.h"
+#include "common/fs/file.h"
+#include "common/fs/fs.h"
+#include "common/fs/fs_util.h"
+#include "common/fs/path_util.h"
+#include "common/logging.h"
+#include "video_core/post_processing/fx_compile.h"
+#include "video_core/post_processing/fx_effect.h"
+
+namespace VideoCore {
+
+namespace {
+
+constexpr u32 CATALOG_PROBE_WIDTH = 1280;
+constexpr u32 CATALOG_PROBE_HEIGHT = 720;
+constexpr u32 CATALOG_PROBE_DEPTH = 8;
+
+std::vector<FxEffectDesc> catalog;
+bool catalog_scanned = false;
+
+const reshadefx::annotation* FindAnnotation(const std::vector<reshadefx::annotation>& annotations,
+                                            std::string_view name) {
+    const auto it = std::find_if(annotations.begin(), annotations.end(),
+                                 [&](const reshadefx::annotation& a) { return a.name == name; });
+    if (it == annotations.end()) {
+        return nullptr;
+    }
+    return &*it;
+}
+
+std::string AnnotationString(const std::vector<reshadefx::annotation>& annotations,
+                             std::string_view name) {
+    const reshadefx::annotation* a = FindAnnotation(annotations, name);
+    if (a == nullptr) {
+        return std::string();
+    }
+    return a->value.string_data;
+}
+
+bool AnnotationFloat(const std::vector<reshadefx::annotation>& annotations, std::string_view name,
+                     f32& out) {
+    const reshadefx::annotation* a = FindAnnotation(annotations, name);
+    if (a == nullptr) {
+        return false;
+    }
+    if (a->type.is_floating_point()) {
+        out = a->value.as_float[0];
+        return true;
+    }
+    if (a->type.is_integral()) {
+        out = static_cast<f32>(a->value.as_int[0]);
+        return true;
+    }
+    return false;
+}
+
+FxUiType ParseUiType(std::string_view value) {
+    if (value == "slider") {
+        return FxUiType::Slider;
+    }
+    if (value == "drag") {
+        return FxUiType::Drag;
+    }
+    if (value == "combo") {
+        return FxUiType::Combo;
+    }
+    if (value == "radio") {
+        return FxUiType::Radio;
+    }
+    if (value == "check" || value == "checkbox") {
+        return FxUiType::CheckBox;
+    }
+    if (value == "color") {
+        return FxUiType::Color;
+    }
+    if (value == "input") {
+        return FxUiType::InputBox;
+    }
+    return FxUiType::Hidden;
+}
+
+std::vector<std::string> SplitItems(const std::string& items) {
+    std::vector<std::string> out;
+    std::string current;
+    for (const char c : items) {
+        if (c == '\0') {
+            out.push_back(current);
+            current.clear();
+            continue;
+        }
+        current += c;
+    }
+    if (!current.empty()) {
+        out.push_back(current);
+    }
+    return out;
+}
+
+FxUniformDesc DescribeUniform(const reshadefx::uniform& info) {
+    FxUniformDesc desc;
+    desc.name = info.name;
+    desc.components = std::min<u32>(info.type.components(), 4);
+
+    if (info.type.is_boolean()) {
+        desc.kind = FxUniformKind::Boolean;
+    } else if (info.type.is_integral()) {
+        desc.kind = FxUniformKind::Integer;
+    } else {
+        desc.kind = FxUniformKind::Floating;
+    }
+
+    desc.label = AnnotationString(info.annotations, "ui_label");
+    if (desc.label.empty()) {
+        desc.label = info.name;
+    }
+    desc.tooltip = AnnotationString(info.annotations, "ui_tooltip");
+    desc.category = AnnotationString(info.annotations, "ui_category");
+    desc.ui_type = ParseUiType(AnnotationString(info.annotations, "ui_type"));
+    desc.items = SplitItems(AnnotationString(info.annotations, "ui_items"));
+
+    if (desc.kind == FxUniformKind::Boolean) {
+        desc.ui_min = 0.0f;
+        desc.ui_max = 1.0f;
+        desc.ui_step = 1.0f;
+    } else if (desc.kind == FxUniformKind::Integer) {
+        desc.ui_min = 0.0f;
+        desc.ui_max = 100.0f;
+        desc.ui_step = 1.0f;
+    }
+
+    void(AnnotationFloat(info.annotations, "ui_min", desc.ui_min));
+    void(AnnotationFloat(info.annotations, "ui_max", desc.ui_max));
+    void(AnnotationFloat(info.annotations, "ui_step", desc.ui_step));
+
+    if (desc.ui_step <= 0.0f) {
+        desc.ui_step = 0.01f;
+        if (desc.kind != FxUniformKind::Floating) {
+            desc.ui_step = 1.0f;
+        }
+    }
+    if (desc.ui_max < desc.ui_min) {
+        std::swap(desc.ui_min, desc.ui_max);
+    }
+
+    if (info.has_initializer_value) {
+        for (u32 i = 0; i < desc.components; ++i) {
+            if (desc.kind == FxUniformKind::Floating) {
+                desc.default_value[i] = info.initializer_value.as_float[i];
+            } else {
+                desc.default_value[i] = static_cast<f32>(info.initializer_value.as_int[i]);
+            }
+        }
+    }
+
+    return desc;
+}
+
+FxEffectDesc DescribeEffect(const std::filesystem::path& path, const std::filesystem::path& root) {
+    FxEffectDesc desc;
+    desc.file = Common::FS::PathToUTF8String(std::filesystem::relative(path, root));
+    desc.name = Common::FS::PathToUTF8String(path.stem());
+
+    const auto compiled =
+        CompileFxEffect(path, CATALOG_PROBE_WIDTH, CATALOG_PROBE_HEIGHT, CATALOG_PROBE_DEPTH);
+    if (!compiled.Succeeded()) {
+        desc.error = compiled.error;
+        return desc;
+    }
+
+    for (const auto& technique : compiled.module.techniques) {
+        desc.techniques.push_back(technique.name);
+    }
+
+    if (!compiled.module.techniques.empty()) {
+        const auto& annotations = compiled.module.techniques.front().annotations;
+        desc.label = AnnotationString(annotations, "ui_label");
+        desc.description = AnnotationString(annotations, "ui_tooltip");
+    }
+    if (desc.label.empty()) {
+        desc.label = desc.name;
+    }
+
+    for (const auto& uniform : compiled.module.uniforms) {
+        FxUniformDesc uniform_desc = DescribeUniform(uniform);
+        if (uniform_desc.ui_type == FxUiType::Hidden) {
+            continue;
+        }
+        desc.uniforms.push_back(std::move(uniform_desc));
+    }
+
+    return desc;
+}
+
+} // Anonymous namespace
+
+std::filesystem::path GetFxRootDirectory() {
+    return Common::FS::GetEdenPath(Common::FS::EdenPath::PostShaderDir);
+}
+
+std::vector<std::filesystem::path> GetFxIncludePaths(const std::filesystem::path& effect_path) {
+    const auto root = GetFxRootDirectory();
+    std::vector<std::filesystem::path> paths;
+    paths.push_back(effect_path.parent_path());
+    paths.push_back(root);
+    paths.push_back(root / "Shaders");
+
+    const auto last = std::unique(paths.begin(), paths.end());
+    paths.erase(last, paths.end());
+    return paths;
+}
+
+std::filesystem::path ResolveFxTexturePath(const std::filesystem::path& effect_path,
+                                           std::string_view source) {
+    const auto root = GetFxRootDirectory();
+    const std::filesystem::path name{source};
+
+    const std::array candidates{
+        effect_path.parent_path() / name,
+        root / "Textures" / name,
+        root / name,
+    };
+
+    for (const auto& candidate : candidates) {
+        if (Common::FS::Exists(candidate)) {
+            return candidate;
+        }
+    }
+
+    return std::filesystem::path();
+}
+
+void ReloadFxCatalog() {
+    catalog.clear();
+    catalog_scanned = true;
+
+    const auto root = GetFxRootDirectory();
+    if (!Common::FS::Exists(root) && !Common::FS::CreateDirs(root)) {
+        return;
+    }
+
+    for (const auto& bundled : BUNDLED_FX_EFFECTS) {
+        const auto path = root / bundled.name;
+        if (Common::FS::Exists(path)) {
+            continue;
+        }
+        void(Common::FS::WriteStringToFile(path, Common::FS::FileType::TextFile, bundled.source));
+    }
+
+    std::vector<std::filesystem::path> effect_files;
+    Common::FS::IterateDirEntriesRecursively(
+        root,
+        [&](const std::filesystem::directory_entry& entry) {
+            if (entry.path().extension() == ".fx") {
+                effect_files.push_back(entry.path());
+            }
+            return true;
+        },
+        Common::FS::DirEntryFilter::File);
+
+    std::sort(effect_files.begin(), effect_files.end());
+
+    for (const auto& file : effect_files) {
+        FxEffectDesc desc = DescribeEffect(file, root);
+        if (!desc.error.empty()) {
+            LOG_WARNING(Render, "Post-processing effect '{}' failed to compile:\n{}", desc.file,
+                        desc.error);
+        }
+        catalog.push_back(std::move(desc));
+    }
+
+    const size_t usable = std::count_if(catalog.begin(), catalog.end(),
+                                        [](const FxEffectDesc& d) { return d.Valid(); });
+    LOG_INFO(Render, "Loaded {} post-processing effects ({} usable)", catalog.size(), usable);
+}
+
+const std::vector<FxEffectDesc>& GetFxCatalog() {
+    if (!catalog_scanned) {
+        ReloadFxCatalog();
+    }
+    return catalog;
+}
+
+const FxEffectDesc* FindFxEffect(std::string_view file) {
+    const auto& effects = GetFxCatalog();
+    const auto it = std::find_if(effects.begin(), effects.end(),
+                                 [&](const FxEffectDesc& d) { return d.file == file; });
+    if (it == effects.end()) {
+        return nullptr;
+    }
+    return &*it;
+}
+
+const FxUniformDesc* FindFxUniform(const FxEffectDesc& effect, std::string_view name) {
+    const auto it = std::find_if(effect.uniforms.begin(), effect.uniforms.end(),
+                                 [&](const FxUniformDesc& u) { return u.name == name; });
+    if (it == effect.uniforms.end()) {
+        return nullptr;
+    }
+    return &*it;
+}
+
+} // namespace VideoCore